Exoplanet Discoveries and Updates

[The Astronomer]

Today we have two interesting news. One is the direct imaging of TYC 8998-760-1, a young solar analog star with two planets, and another is the detection of transits of the known planets around the star Nu2 Lupi.

A star some three hundred light-years away, TYC 8998-760-1 was already known to host one planet, detected by direct imaging. The new image reveals the presence of its sibling planet, which is smaller and probably further away from the star than the first planet.

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TYC 8998-760-1 b
Projected physical separation: 160 AU
Mass: 14 Jupiters

TYC 8998-760-1 c
Projected physical separation: 320 AU
Mass: 6 Jupiters
Radius: 1.1 Jupiters
Effective temperature: 1240 K

Closer to home we have Nu2 Lupi, which is colonized as NewRoot in Orion's Arm. The system has three known planets occupying mass ranges from 4-11 Earth masses. With the detection of transits of these planets, it is now possible to find both radii and true masses, the two keys to figuring out density and thus a rough but solid idea of what the planet is like. Combined with improved radial velocity data yields a vastly expanded view of the inner Nu2 Lupi system.

(LINK)

Nu2 Lupi b
Semi-major axis: 0.0969 AU
Orbital period: 11.57779 days
Eccentricity: 0.079
Inclination: 88.86 degrees
Mass: 4.62 Earths
Radius: 1.482 Earths
Equilibrium temperature: 911 K


Nu2 Lupi c
Semi-major axis: 0.1729 AU
Orbital period: 27.5909 days
Eccentricity: 0.037
Inclination: 88.658 degrees
Mass: 11.29 Earths
Radius: 2.608 Earths
Equilibrium temperature: 682 K

Nu2 Lupi d
Semi-major axis: 0.4285 AU
Orbital period: 107.63 days
Eccentricity: 0.075
Minimum mass: 10.5 Earths
Equilibrium temperature: 433.3 K

This measurement confirms that Nu2 Lupi b is a dense rocky planet, while Nu2 Lupi c is a gaseous planet. While its actual radius is not available, judging from its mass, Nu2 Lupi d is most likely to also be a Neptunian.
If Nu2 Lupi d is aligned with the other two planets, it wouldn't transit the star.